Warming up is absolutely crucial : you need to get your body ready for physical activity. Even if the bar exercises seem harsh and difficult, they’re necessary, so make sure you do them properly. Think about working your joints, upper limbs and neck properly, and don’t forget to warm up your abs either, because you use them all the time when you’re dancing.
The good news is that there’s not much you need to do after class. Just wind down and do some stretching to keep the elasticity in your muscles. Don’t forget your bottle of water: make sure you drink plenty to avoid dehydration.